Mix turmeric and cumin powders, yoghurt, raw garlic, roasted onion, white onion and white pepper powder in a blender, blend and keep it aside.
Grate the cucumber and add it to the above blended mixture. Mix well with hand and add salt.
Keep this mixture in a chiller for 30 minutes
Dice vegetables and just add the dressing blend, serve immediately.
Note:
Do not mix the dressing and keep in the chiller for a long time.